CERAD, the Consortium to Establish a Registry for Alzheimer's Disease, was established to develop brief, standardized, valid, and reliable assessments and procedures for the identification and evaluation of subjects with Alzheimer's disease. CERAD has not only accomplished these tasks but has also developed and tested standardized assessments of the behavioral and personality changes, family history, parkinsonian signs, and social service needs associated with this illness. The study has expanded from its original 11 clinical sites to become a multi-center network of 24 university medical center sites in the US and their satellites. It has successfully conducted follow-up observations, obtained a high rate of autopsies, and translated its protocols into a number of foreign languages. By applying its existing assessment instruments, the CERAD study proposes to: (1) continue annual follow-up observations of the present cohort of CERAD subjects and achieve a high rate of autopsies; (2) explore the database to define subtypes of AD and to document their heterogeneity by means of clinical patterns, rates of decline, and neuropathological findings; (3) expand the present CERAD neuropathological evaluation to include non- AD dementias in order to provide powerful clinical-neuropathological correlations; (4) adopt appropriate statistical methods and enhance quality control procedures for the studies outlined above.